The national Youth Risk Behavior Survey (YRBS) monitors priority health risk behaviors that contribute to the leading causes of death, disability, and social problems among youth and adults in the United States. The national YRBS is conducted every two years during the spring semester and provides data representative of 9th through 12th grade students in public and private schools throughout the United States. This fact sheet presents trends in the prevalence of behaviors that contribute to violence on school property from 1991 to 2011. (Contains 4 endnotes.)